Reduce to lowest terms: $ \dfrac{3}{8} \div - \dfrac{3}{7} = {?}$
Dividing by a fraction is the same as multiplying by the reciprocal of the fraction. The reciprocal of $- \dfrac{3}{7}$ is $- \dfrac{7}{3}$ Therefore: $ \dfrac{3}{8} \div - \dfrac{3}{7} = \dfrac{3}{8} \times - \dfrac{7}{3} $ $ \phantom{ \dfrac{3}{8} \times - \dfrac{7}{3}} = \dfrac{3 \times -7}{8 \times 3} $ $ \phantom{ \dfrac{3}{8} \times - \dfrac{7}{3}} = \dfrac{-21}{24} $ The numerator and denominator have a common divisor of $3$, so we can simplify: $ \dfrac{-21}{24} = \dfrac{-21 \div 3}{24 \div 3} = -\dfrac{7}{8} $